I guess it depends where you holiday.
If I'm going on a trip that includes diving, I'll take a diver with me (Usually my Longines HC if it's localish and my DN Voyager for longer hauls, although it's not set in stone) and wear that all week.
Otherwise, I'll just pick one watch at random and wear that for the duration.
Last year I holidayed in Val D'Isere (HC I think), Malta (errr....I forget...), Stockholm (nope, no idea...) and Lanzarote (CW Makaira).
This year it's Zermatt (Sinn), Indonesia (DN Voyager) and Azores (a diver, tbd!).
I'd agree with the sentiment about buying watches you're afraid to wear in public, but equally I've a friend from Rio who always warns me not to wear any semi-decent watch there, even in the better areas (I've never actually been to Rio, but forewarned... ), so I guess it's a case of applying sensible logic to the environment you'll be in.
If you're going to get mugged in a dodgy area, the thieves will want cash and cards and jewellery. They'll take your Rolex, but if it's that dodgy an area, they'll probably assume it's a fake anyway!
On topic, if it's a sandy beach rubber, otherwise bracelet.
M.